As a key regulator of energy storage and energy balance, insulin is an obvious suspect as the body set weight regulator. If insulin causes obesity, it must do so predominantly through its effect in the brain. Obesity is controlled in the central nervous system through the body set weight, not in the periphery. In this hypothesis, high insulin levels increase the body set weight. Certainly, the insulin response differs greatly between lean and obese patients. Obese patients1 tend to have a higher fasting insulin level, as well as an exaggerated insulin response to food.
